Commit 63235141 authored Nov 23, 2017 by Gal Pressman Committed by Saeed Mahameed Dec 19, 2017

net/mlx5e: Fix possible deadlock of VXLAN lock



mlx5e_vxlan_lookup_port is called both from mlx5e_add_vxlan_port (user
context) and mlx5e_features_check (softirq), but the lock acquired does
not disable bottom half and might result in deadlock. Fix it by simply
replacing spin_lock() with spin_lock_bh().
While at it, replace all unnecessary spin_lock_irq() to spin_lock_bh().

lockdep's WARNING: inconsistent lock state
[  654.028136] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[  654.028229] swapper/5/0 [HC0[0]:SC1[9]:HE1:SE0] takes:
[  654.028321]  (&(&vxlan_db->lock)->rlock){+.?.}, at: [<ffffffffa06e7f0e>] mlx5e_vxlan_lookup_port+0x1e/0x50 [mlx5_core]
[  654.028528] {SOFTIRQ-ON-W} state was registered at:
[  654.028607]   _raw_spin_lock+0x3c/0x70
[  654.028689]   mlx5e_vxlan_lookup_port+0x1e/0x50 [mlx5_core]
[  654.028794]   mlx5e_vxlan_add_port+0x2e/0x120 [mlx5_core]
[  654.028878]   process_one_work+0x1e9/0x640
[  654.028942]   worker_thread+0x4a/0x3f0
[  654.029002]   kthread+0x141/0x180
[  654.029056]   ret_from_fork+0x24/0x30
[  654.029114] irq event stamp: 579088
[  654.029174] hardirqs last  enabled at (579088): [<ffffffff818f475a>] ip6_finish_output2+0x49a/0x8c0
[  654.029309] hardirqs last disabled at (579087): [<ffffffff818f470e>] ip6_finish_output2+0x44e/0x8c0
[  654.029446] softirqs last  enabled at (579030): [<ffffffff810b3b3d>] irq_enter+0x6d/0x80
[  654.029567] softirqs last disabled at (579031): [<ffffffff810b3c05>] irq_exit+0xb5/0xc0
[  654.029684] other info that might help us debug this:
[  654.029781]  Possible unsafe locking scenario:

[  654.029868]        CPU0
[  654.029908]        ----
[  654.029947]   lock(&(&vxlan_db->lock)->rlock);
[  654.030045]   <Interrupt>
[  654.030090]     lock(&(&vxlan_db->lock)->rlock);
[  654.030162]
 *** DEADLOCK ***

Fixes: b3f63c3d ("net/mlx5e: Add netdev support for VXLAN tunneling")
Signed-off-by: Gal Pressman <galp@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

parent dbff26e4

drivers/net/ethernet/mellanox/mlx5/core/vxlan.c

+10 −10

Original line number	Diff line number	Diff line
		@@ -71,9 +71,9 @@ struct mlx5e_vxlan mlx5e_vxlan_lookup_port(struct mlx5e_priv priv, u16 port)
		struct mlx5e_vxlan_db *vxlan_db = &priv->vxlan;
		struct mlx5e_vxlan *vxlan;

		spin_lock(&vxlan_db->lock);
		spin_lock_bh(&vxlan_db->lock);
		vxlan = radix_tree_lookup(&vxlan_db->tree, port);
		spin_unlock(&vxlan_db->lock);
		spin_unlock_bh(&vxlan_db->lock);

		return vxlan;
		}
		@@ -100,9 +100,9 @@ static void mlx5e_vxlan_add_port(struct work_struct *work)

		vxlan->udp_port = port;

		spin_lock_irq(&vxlan_db->lock);
		spin_lock_bh(&vxlan_db->lock);
		err = radix_tree_insert(&vxlan_db->tree, vxlan->udp_port, vxlan);
		spin_unlock_irq(&vxlan_db->lock);
		spin_unlock_bh(&vxlan_db->lock);
		if (err)
		goto err_free;

		@@ -121,9 +121,9 @@ static void __mlx5e_vxlan_core_del_port(struct mlx5e_priv *priv, u16 port)
		struct mlx5e_vxlan_db *vxlan_db = &priv->vxlan;
		struct mlx5e_vxlan *vxlan;

		spin_lock_irq(&vxlan_db->lock);
		spin_lock_bh(&vxlan_db->lock);
		vxlan = radix_tree_delete(&vxlan_db->tree, port);
		spin_unlock_irq(&vxlan_db->lock);
		spin_unlock_bh(&vxlan_db->lock);

		if (!vxlan)
		return;
		@@ -171,12 +171,12 @@ void mlx5e_vxlan_cleanup(struct mlx5e_priv *priv)
		struct mlx5e_vxlan *vxlan;
		unsigned int port = 0;

		spin_lock_irq(&vxlan_db->lock);
		spin_lock_bh(&vxlan_db->lock);
		while (radix_tree_gang_lookup(&vxlan_db->tree, (void **)&vxlan, port, 1)) {
		port = vxlan->udp_port;
		spin_unlock_irq(&vxlan_db->lock);
		spin_unlock_bh(&vxlan_db->lock);
		__mlx5e_vxlan_core_del_port(priv, (u16)port);
		spin_lock_irq(&vxlan_db->lock);
		spin_lock_bh(&vxlan_db->lock);
		}
		spin_unlock_irq(&vxlan_db->lock);
		spin_unlock_bh(&vxlan_db->lock);
		}